Background Evidence-based cardiac therapies are underutilized in elderly patients. We assessed differences in practice patterns, comorbidities, and in-hospital event rates, by age and type of acute coronary syndrome (ACS).Methods We studied 24165 ACS patients in 102 hospitals in 14 countries stratified by age.Results Approximately two-thirds of patients were men, but this proportion decreased with age. in elderly patients ( greater than or equal to 65 years), history of angina, transient ischemic attack/stroke, myocardial infarction(MI), congestive heart failure, coronary artery bypass graft (CABG) surgery, hypertension or atrial fibrillation were more common, and delay in seeking medical attention and non-ST-segment elevation MI were significantly higher. Aspirin, beta-blockers, thrombolytic therapy, statins and glycoprotein Ilb/Illa inhibitors were prescribed less, while calcium antagonists and angiotensin-converting enzyme inhibitors were prescribed more often to elderly patients. Unfractionated heparin was prescribed more often in young patients, while low-molecular-weight heparins were similarly prescribed across all age groups. Coronary angiography and percutaneous intervention rates significantly decreased with age. the rate of CABG surgery was highest among patients aged 65-74 years (8.1 %) and 55-6A years (7.7%), but reduced in the youngest (4.7%) and oldest (2.7%) groups. Major bleeding rates were,2-3% among patients aged < 65 years, and > 6% in those : 85 years. Hospital-mortality rates, adjusted for baseline risk differences, increased with age (odds ratio: 15.7 in patients greater than or equal to 85 years compared with those < 45 years).Conclusions Many elderly ACS patients do not receive evidence-based therapies, highlighting the need for clinical trials targeted specifically at elderly cohorts, and quality-of-care programs that reinforce the use of such therapies among these individuals.